The present invention relates to a lifting device for picking up a member from the bottom of the sea, the lifting device comprising a body, a housing and an engagement member coupled with the body and the housing such that the engagement member is moveably arranged to move in a radial direction with respect to the central axis. An example of this type of lifting device of the present invention is referred to as to internal lifting tool in the field.
Such a lifting device is known from GB1577778 which relates to lifting devices for tubular piles. GB1577778 provides a pipe lifting device having a plurality of latches movably mounted on the body and moveable between retracted positions and extended positions in which the latches project laterally of the body. The latches can be operated by a weight means and a drawing line.
Incorporating a free weight in the lifting device complicates the design and a drawing line is cumbersome in use during operations at the bottom of the sea.
Offshore lifting devices frequently put objects down on the seabed and pick these objects from the seabed later. Many times it is desirable that no connection between the lifting device and the vessel is maintained during the time that the object is down on the seabed. It is then required to make connection again with the object for lifting the object off the seabed. There are already different ways of doing this such as connect slings around trunnions, connect a shackle to the object or lower an internal lifting tool into a piece of pipe on the object. Such an Internal Lifting Tool (ILT) needs to be connected hydraulically to a powerpack to be activated. In most cases this is a powerpack on the vessel, but it can also be a subsea powerpack or a set of hydraulic accumulators. At all times this complicates the use of an ILT.
EP 0257943 relates to an apparatus for use in energy exploration and includes a support tubular member for connection to a drilling string, and a radially movable member to pass through tubular obstructions.